Drug eluting stents have become popular medical devices. One difficulty with such devices is the difficulty in binding the drug to the stent and controlling drug elution. Previously, this problem has been addressed by incorporating the drug, often rapamycin, sirolimus, or the like, within a polymer and layering the drug polymer on a stent surface.
The polymer coating process generally requires a solvent, in which the drugs are usually soluble, and thus limits the ability to control elution of one or more therapeutic agents. It is therefore desirable to provide a drug coated stent without polymeric vehicles to deliver the drug.
The biocompatibility of polymers has come into question. A degradable coating may provide biocompatibility advantages over permanent polymer coatings in allowing the tissue to eventually come into direct contact with the bulk stent material.
Polymer coatings commonly have problems with durability, which may put patients at risk of embolism, and also prevent their use on self-expanding stent platforms.
Polymer coatings face limitations of elution control. It is therefore desirable to have a coating with improved elution control.
It would be desirable, therefore, to provide a substantially polymer-free drug coated stent that would overcome the limitations and disadvantages inherent in the devices described above.